1. Field of the Invention
The invention relates to a marine energy cell construction and more particularly to a mounting construction for supporting a barrier or bumper frame on a plurality of adjacent leg or upright members of a marine or offshore oil rig, docking platform, loading dock or the like to substantially reduce the harmful effect of lateral components of forces to which a barrier frame is subjected when ship, barge or other floating vessel movement nonperpendicular to the general plane of the barrier frame is arrested by the barrier to stop further headway of the vessel during docking.
In addition, the invention relates to a marine structure barrier mounting construction having two different types of energy-absorbing units cooperatively connected so that one unit absorbs energy primarily from resultant force components directed normal to the plane of the barrier frame and the other unit absorbs energy primarily from resultant force components directed parallel to the plane of the barrier frame, said resultant forces being components of the angular direction of ship movement stopped by the barrier frame. This is not to say that either of the units just described do not absorb energy in directions other than those stated.
2. Description of the Prior Art
Traditionally barrier frames for marine docking facilities have been supported extending above and below the water line on shock cells mounted on at least two spaced legs or other upright columns of a docking structure. Such barrier frames usually have consisted of a latticelike rigid assembly of horizontal and vertical metal pipes or the like and may also include trusslike reinforcement of the frame against bending.
Usually vertical pipe members at the ends of the barrier frame are welded to or otherwise mounted in fixed relation with respect to the outer ends of inner cylinder members of shock cells. Such prior shock cells are of a type having outer cylindrical pipe members mounted in fixed position on spaced upright columns of the docking facility structure, and the shock cell inner and outer cylinder members are joined by an intervening rubber sleeve. The shock cells thus absorb energy resulting from the resultant force components normal to the plane of the barrier frame of ship movement stopped by the barrier frame.
Such barriers and barrier mountings function satisfactorily as long as the ship movement force to be absorbed by the shock cells is directed normal to the plane of the barrier frame, or as long as the resultant horizontal component of such force (if the force is angularly directed against the barrier frame) directed normal to the plane of the barrier frame is of great magnitude as compared with the relative resultant component of said force directed parallel to the plane of the barrier frame.
However, when said "parallel" resultant component of the ship movement force is of great magnitude it tends to move the barrier frame laterally in its plane in one direction or the other. This puts stress on the fixed mounting of the barrier frame on the ends of the projecting shock cell inner cylinder members which may break or cause failure of the welded connection or other fixed mounting means of the horizontal barrier members that are welded or otherwise fixed to the outer ends of the inner cylinder shock cell members.
Such failure of a barrier mounting on a marine docking facility, particularly on offshore oil rig structures, results in substantial barrier repair or replacement costs.
I am unaware of any practical solution of the described problem that long has existed in the construction and use of marine docking facility barriers for fending off and stopping ship movement at the docking facility.
Accordingly, there is an unsatisfied need existing in the art for a mounting construction for marine docking facility barriers which functions to absorb energy when the barrier stops ship movement, regardless of the direction of ship movement when contacting the barrier, without damage to the barrier or its mounting.